Direct Growth of BODIPY‐Based Conjugated Porous Polymer Shell on Upconversion Nanoparticles for NIR‐Driven Photocatalysis

ABSTRACT The great applications of upconversion nanoparticles (UCNPs) can be further extended by their encapsulation within conjugated porous polymers (CPPs). However, the synthesis of monodisperse core@shell based CPPs upconversion nanohybrids remains a challenge. Herein, we report a simple, general strategy that combines (i) prefunctionalization of UCNPs with polymerizable units, (ii) monomer‐feed control, and (iii) a centrifugation‐based work‐up to ensure anchoring to the inorganic core. This approach enables covalent growth of CPP shells with tunable thickness and low polydispersity. Thus, a BODIPY‐based CPP shell was grown over both core (NaYF 4 : Yb 3+ (20%), Er 3+ (2%)) and core‐shell (NaYF 4 : Yb 3+ (20%), Er 3+ (2%)@NaYF 4 ) UCNPs, yielding UC C @CPP and UC CS @CPP nanohybrids. Under near‐infrared (NIR) excitation, the UCNP core upconverts light to activate the surrounding CPP shell leading to photocatalytic activity. UC CS @CPP exhibits a twofold higher photocatalytic activity than UC C @CPP highlighting the critical role of the NaYF 4 passivation layer in preserving upconversion efficiency. Our approach overcomes key limitations of previous designs achieving improved photooxidation yields (i.e., 42%) and excellent recyclability. This modular platform provides a robust and versatile route to UC@CPP hybrids for designing NIR‐driven, reactive oxygen species (ROS)‐generating photocatalysts.